# MKR Zero **URL:** https://forum.arduino.cc/c/official-hardware/mkr-boards/mkr-zero/140.md [Latest](https://forum.arduino.cc/latest.md) · [Categories](https://forum.arduino.cc/categories.md) --- ## [How to get the best out of this forum](https://forum.arduino.cc/t/how-to-get-the-best-out-of-this-forum/1417917)
**Author:** [@system](https://forum.arduino.cc/u/system)\ **Replies:** 0\ **Last updated:** [December 4, 2025, 2:48pm UTC](https://forum.arduino.cc/t/how-to-get-the-best-out-of-this-forum/1417917 "2025-12-04T14:48:50Z")
Welcome to the Arduino forum! A guide explaining how to get the best out of this forum is available at the link below. Please read it: --- ## [About the MKR Zero category](https://forum.arduino.cc/t/about-the-mkr-zero-category/847580)
**Author:** [@system](https://forum.arduino.cc/u/system)\ **Replies:** 0\ **Last updated:** [April 12, 2021, 12:19pm UTC](https://forum.arduino.cc/t/about-the-mkr-zero-category/847580 "2021-04-12T12:19:32Z")
The MKRZero brings you the power of a Zero in the smaller format established by the MKR form factor --- ## [Read the microSD card detect pin PA27 (pin 30)](https://forum.arduino.cc/t/read-the-microsd-card-detect-pin-pa27-pin-30/1426198)
**Author:** [@jsteward](https://forum.arduino.cc/u/jsteward)\ **Replies:** 0\ **Last updated:** [January 20, 2026, 12:05am UTC](https://forum.arduino.cc/t/read-the-microsd-card-detect-pin-pa27-pin-30/1426198 "2026-01-20T00:05:41Z")
The circuit diagram shows a Card Detect connection from the microSD card slot to PA27 with no pullup. I think the card slot should ground the pin when a card is inserted, or the other way around. The pin isn't defined … --- ## [Using Two MAX30102 Sensors on Arduino MKR Zero Without a Multiplexer](https://forum.arduino.cc/t/using-two-max30102-sensors-on-arduino-mkr-zero-without-a-multiplexer/1409219)
**Author:** [@andrecampa](https://forum.arduino.cc/u/andrecampa)\ **Replies:** 10\ **Last updated:** [October 14, 2025, 7:17pm UTC](https://forum.arduino.cc/t/using-two-max30102-sensors-on-arduino-mkr-zero-without-a-multiplexer/1409219 "2025-10-14T19:17:23Z")
Hi everyone, I'm trying to read data from two MAX30102 sensors on an Arduino MKR Zero, but I’m running into several issues. I’d like a solution without using a multiplexer (if there’s no way around it, I can consider on… --- ## [MKR Zero running on battery](https://forum.arduino.cc/t/mkr-zero-running-on-battery/1394789)
**Author:** [@RogerHartley](https://forum.arduino.cc/u/RogerHartley)\ **Replies:** 4\ **Last updated:** [July 29, 2025, 9:48am UTC](https://forum.arduino.cc/t/mkr-zero-running-on-battery/1394789 "2025-07-29T09:48:34Z")
Hi, First time poster here so apologies in advance. I've read several posts about this issue but none have come close to solving this. I'm trying to run the MKR Zero from the attached 3.7v 2000mAh 7.4Wh lipo battery. The… --- ## [Working MKR Zero with battery](https://forum.arduino.cc/t/working-mkr-zero-with-battery/1391099)
**Author:** [@herz\_tau](https://forum.arduino.cc/u/herz_tau)\ **Replies:** 8\ **Last updated:** [June 23, 2025, 5:07pm UTC](https://forum.arduino.cc/t/working-mkr-zero-with-battery/1391099 "2025-06-23T17:07:30Z")
I bought several Arduino Zero boards and they all behave the same. The charge indicator LED (DL2) is constantly lit when the board is powered from the USB, regardless of whether the battery is connected or not. It seem… --- ## [Buzzing from MKR Zero DAC pin](https://forum.arduino.cc/t/buzzing-from-mkr-zero-dac-pin/1378530)
**Author:** [@biochem1991](https://forum.arduino.cc/u/biochem1991)\ **Replies:** 5\ **Last updated:** [May 2, 2025, 7:25pm UTC](https://forum.arduino.cc/t/buzzing-from-mkr-zero-dac-pin/1378530 "2025-05-02T19:25:42Z")
Hi all. This is my first post and I hope it's in the right place. I found several other discussions around this issue but with no resolution. I am having issues with my MKR Zero where there is a loud, low pitched buzzin… --- ## [Battery to MKR ZERO not working](https://forum.arduino.cc/t/battery-to-mkr-zero-not-working/1363931)
**Author:** [@jdjwubs626](https://forum.arduino.cc/u/jdjwubs626)\ **Replies:** 2\ **Last updated:** [March 16, 2025, 11:19am UTC](https://forum.arduino.cc/t/battery-to-mkr-zero-not-working/1363931 "2025-03-16T11:19:48Z")
I have sauldered a battery attachment to power my Mkr zero with a 9v battery however it doesnt work, the battery for sure Works as i tested it with a nano. What could be the issue here? --- ## [MKRZero Only Uploads in Bootloader Mode](https://forum.arduino.cc/t/mkrzero-only-uploads-in-bootloader-mode/1354757)
**Author:** [@15wileyr](https://forum.arduino.cc/u/15wileyr)\ **Replies:** 2\ **Last updated:** [February 17, 2025, 5:26pm UTC](https://forum.arduino.cc/t/mkrzero-only-uploads-in-bootloader-mode/1354757 "2025-02-17T17:26:44Z")
Hello I'm aware of the "Native USB" quirks of this family of boards. Mine will only accept uploads if it is in bootloader mode and even then only works a quarter of the time. This is with multiple cables, and with Blink… --- ## [Windows 10 won't recognize MKR Zero?](https://forum.arduino.cc/t/windows-10-wont-recognize-mkr-zero/1288442)
**Author:** [@jmcebula10633](https://forum.arduino.cc/u/jmcebula10633)\ **Replies:** 8\ **Last updated:** [January 16, 2025, 3:12pm UTC](https://forum.arduino.cc/t/windows-10-wont-recognize-mkr-zero/1288442 "2025-01-16T15:12:32Z")
Hi all! I'm trying to get some code onto a MKR Zero. My computer doesn't react when I plug in the board. On the board itself, the green LED is steady on, the yellow LED is slowly (1sec on, 1 sec off) blinking. The ID… --- ## [How to program arduino mkr zero in C with VScode, armgcc and bossac](https://forum.arduino.cc/t/how-to-program-arduino-mkr-zero-in-c-with-vscode-armgcc-and-bossac/1332447)
**Author:** [@nicoduinomg](https://forum.arduino.cc/u/nicoduinomg)\ **Replies:** 1\ **Last updated:** [December 16, 2024, 5:19pm UTC](https://forum.arduino.cc/t/how-to-program-arduino-mkr-zero-in-c-with-vscode-armgcc-and-bossac/1332447 "2024-12-16T17:19:05Z")
Hello everyone, I want to program my arduino only with vscode, armgcc and bossac. Currently, I downloaded a CMSIS from here GitHub - ARMmbed/cmsis-core-atmel-samcortexm0p-samd21: CMSIS Core Implementation for Atmel SAMD… --- ## [Simcom7600 and Atecc608 use hardware cert mqtt](https://forum.arduino.cc/t/simcom7600-and-atecc608-use-hardware-cert-mqtt/1292022)
**Author:** [@alexandersson\_1510](https://forum.arduino.cc/u/alexandersson_1510)\ **Replies:** 3\ **Last updated:** [August 15, 2024, 7:57am UTC](https://forum.arduino.cc/t/simcom7600-and-atecc608-use-hardware-cert-mqtt/1292022 "2024-08-15T07:57:47Z")
I want to know how to use atecc608 certificate with simcom7600 to use Mqtt(s) protocol AWS Iot Core BOARD: Arduino MKR ZERO --- ## [SAM D21 - Output 3 clock signals on 3 pins](https://forum.arduino.cc/t/sam-d21-output-3-clock-signals-on-3-pins/1289451)
**Author:** [@fgotham](https://forum.arduino.cc/u/fgotham)\ **Replies:** 1\ **Last updated:** [August 7, 2024, 3:34pm UTC](https://forum.arduino.cc/t/sam-d21-output-3-clock-signals-on-3-pins/1289451 "2024-08-07T15:34:31Z")
I've got a SAM D21 microcontroller. I want to use 3 output pins to output 3 clock signals: high clock = 8 MHz mid clock = 32.768 kHz low clock = 8.192 kHz In the datasheet under the section Multiplexed Signals, under t… --- ## [Troubles using UART](https://forum.arduino.cc/t/troubles-using-uart/1274083)
**Author:** [@giuggiodk](https://forum.arduino.cc/u/giuggiodk)\ **Replies:** 22\ **Last updated:** [June 27, 2024, 4:14pm UTC](https://forum.arduino.cc/t/troubles-using-uart/1274083 "2024-06-27T16:14:23Z")
Hello, I'm fighting with reading data through UART, which is not as expected. I have a signal as in the attached image. The waveform is taken from PIN 13, UART RX. The device in question is a SSS-Siedle door system wit… --- ## [Arduino MKR Zero "Device Descriptor Failed"](https://forum.arduino.cc/t/arduino-mkr-zero-device-descriptor-failed/1229183)
**Author:** [@deshbhakt](https://forum.arduino.cc/u/deshbhakt)\ **Replies:** 1\ **Last updated:** [June 5, 2024, 9:12pm UTC](https://forum.arduino.cc/t/arduino-mkr-zero-device-descriptor-failed/1229183 "2024-06-05T21:12:10Z")
I have a Arduino MKR Zero and I have a script flashed to work as a keyboard and type "Hello world". I am not sure why sometimes it gets connected as a COM port and works as intended while many a times, the Device Manage… --- ## [MKR Zero and MKR CAN Shield](https://forum.arduino.cc/t/mkr-zero-and-mkr-can-shield/1262324)
**Author:** [@bfpa40](https://forum.arduino.cc/u/bfpa40)\ **Replies:** 3\ **Last updated:** [May 21, 2024, 4:16am UTC](https://forum.arduino.cc/t/mkr-zero-and-mkr-can-shield/1262324 "2024-05-21T04:16:19Z")
Is there already a sketch present somewhere that takes Data coming in from the Shield on the SPI and saves it to the SD Card? I am trying (unsuccessfully so far) to get the CAN Shield to bring CAN Data in and save it to … --- ## [Button press to keyboard input](https://forum.arduino.cc/t/button-press-to-keyboard-input/1251168)
**Author:** [@SouthernSoup533](https://forum.arduino.cc/u/SouthernSoup533)\ **Replies:** 4\ **Last updated:** [April 23, 2024, 1:48pm UTC](https://forum.arduino.cc/t/button-press-to-keyboard-input/1251168 "2024-04-23T13:48:32Z")
I'm trying to have a button press input a keystroke. I'm using the MKR Zero board, and it is not currently working properly. The LED lights up when the button is pressed, but no keystroke is inputted. Eventually, I plan … --- ## [Arduino MKR Zero Keyboard Emulation not working](https://forum.arduino.cc/t/arduino-mkr-zero-keyboard-emulation-not-working/1228020)
**Author:** [@deshbhakt](https://forum.arduino.cc/u/deshbhakt)\ **Replies:** 4\ **Last updated:** [February 24, 2024, 7:51pm UTC](https://forum.arduino.cc/t/arduino-mkr-zero-keyboard-emulation-not-working/1228020 "2024-02-24T19:51:43Z")
I bought a new Arduino MKR Zero which is generally promoted for playing sound from SD Card (SD card slot built-in on the board) but since the Microcontroller is SAMD21, I believe it supports keyboard emulation. I am try… --- ## [Does the board reset after LowPower.deepSleep() call?](https://forum.arduino.cc/t/does-the-board-reset-after-lowpower-deepsleep-call/1227736)
**Author:** [@psyon](https://forum.arduino.cc/u/psyon)\ **Replies:** 3\ **Last updated:** [February 23, 2024, 11:45pm UTC](https://forum.arduino.cc/t/does-the-board-reset-after-lowpower-deepsleep-call/1227736 "2024-02-23T23:45:50Z")
A comment in the PrimoDeepSleep example states that the board will reset when coming out of deep sleep. This doesn't appear to be the case when I am using it. Is that only for specific boards or specific wake up even… --- ## [HC 05 Short Circuit on Arduino MKRZero](https://forum.arduino.cc/t/hc-05-short-circuit-on-arduino-mkrzero/1214612)
**Author:** [@AZYE104](https://forum.arduino.cc/u/AZYE104)\ **Replies:** 1\ **Last updated:** [January 22, 2024, 11:04pm UTC](https://forum.arduino.cc/t/hc-05-short-circuit-on-arduino-mkrzero/1214612 "2024-01-22T23:04:26Z")
Hello, I connected power supply to breadboard. Then I connect the Arduino MKRZero power pins and HC-05 Bluetooth power pins to the power line of the breadboard. I got short circuit error on my power supply. Do you have … --- ## [Sensor controlled volume](https://forum.arduino.cc/t/sensor-controlled-volume/1209886)
**Author:** [@simonchendry](https://forum.arduino.cc/u/simonchendry)\ **Replies:** 4\ **Last updated:** [January 12, 2024, 8:52am UTC](https://forum.arduino.cc/t/sensor-controlled-volume/1209886 "2024-01-12T08:52:10Z")
Hi all. I am trying to make an audio player that will fade in and out depending on an analog input data stream from a sensor. I have got the audio to play out of the DAC0 pin from the SD card successfully but cant find a… --- ## [MKRZERO only uploads in bootloader mode](https://forum.arduino.cc/t/mkrzero-only-uploads-in-bootloader-mode/1207275)
**Author:** [@whatsanarduino](https://forum.arduino.cc/u/whatsanarduino)\ **Replies:** 1\ **Last updated:** [January 6, 2024, 9:36am UTC](https://forum.arduino.cc/t/mkrzero-only-uploads-in-bootloader-mode/1207275 "2024-01-06T09:36:42Z")
I just recently purchased a Arduino MKRZERO official version (Not a third party). For the life of me I can not get the program to upload unless I double tap the reset button and put it in bootloader mode. Once in bootlo… --- ## [Adding buttons to the MKRZero](https://forum.arduino.cc/t/adding-buttons-to-the-mkrzero/1207151)
**Author:** [@dummie1138](https://forum.arduino.cc/u/dummie1138)\ **Replies:** 1\ **Last updated:** [January 4, 2024, 10:14pm UTC](https://forum.arduino.cc/t/adding-buttons-to-the-mkrzero/1207151 "2024-01-04T22:14:39Z")
Hi. I'm trying to move from using the MKRZero on a breadboard to a more mobile physical platform, and would like to know what "shield" can fit additional buttons. The shields I've looked at so far are mostly for differen… --- ## [Nothing will compile and COM port doesn't exist](https://forum.arduino.cc/t/nothing-will-compile-and-com-port-doesnt-exist/1191971)
**Author:** [@bananaboy44](https://forum.arduino.cc/u/bananaboy44)\ **Replies:** 4\ **Last updated:** [November 22, 2023, 5:41pm UTC](https://forum.arduino.cc/t/nothing-will-compile-and-com-port-doesnt-exist/1191971 "2023-11-22T17:41:17Z")
After trying like 4 different USB cables to get the board to even show up in IDE I'm unable to upload nor compile anything. When i went to try and reset the Bootloader and i double press the reset button on the board the… --- ## [MKRZero: TFT.h is not compatile with SAMD21 controller of MKRZero?](https://forum.arduino.cc/t/mkrzero-tft-h-is-not-compatile-with-samd21-controller-of-mkrzero/1173032)
**Author:** [@FrFrau](https://forum.arduino.cc/u/FrFrau)\ **Replies:** 3\ **Last updated:** [November 9, 2023, 10:56am UTC](https://forum.arduino.cc/t/mkrzero-tft-h-is-not-compatile-with-samd21-controller-of-mkrzero/1173032 "2023-11-09T10:56:26Z")
Hallo, I'm using an MKRZero board and I would like to display the output of my project on a 1.8" TFT display that requires Adafruit ST7735 TFT Library. Unfortunately, compiling the sketch I get the error, referred to A… --- ## [MKR IoT Carrier with MkrZero SD card not recognized](https://forum.arduino.cc/t/mkr-iot-carrier-with-mkrzero-sd-card-not-recognized/1180480)
**Author:** [@smarco](https://forum.arduino.cc/u/smarco)\ **Replies:** 4\ **Last updated:** [October 23, 2023, 11:13am UTC](https://forum.arduino.cc/t/mkr-iot-carrier-with-mkrzero-sd-card-not-recognized/1180480 "2023-10-23T11:13:34Z")
Hi everyone, I try to connect a micro-SD card to MKR IoT Carrier rev2 with powered by MKRZero. The MKRZero has a builtin micro-SD card holder on dedicated SPI (which works well with my SD car) but it is not very access… --- ## [SAMD21 TC4 counter ...missing ticks ?](https://forum.arduino.cc/t/samd21-tc4-counter-missing-ticks/1178038)
**Author:** [@nickroman0](https://forum.arduino.cc/u/nickroman0)\ **Replies:** 0\ **Last updated:** [October 13, 2023, 2:57pm UTC](https://forum.arduino.cc/t/samd21-tc4-counter-missing-ticks/1178038 "2023-10-13T14:57:13Z")
I'm trying to detect the oscillation frequency of an LC tank. Code is based on the ingenious work of MartinL : D1 outputs a fixed PWM that triggers the A2 pin interrupt and the ISR captures the TC4 count from D6. The p… --- ## [Difference between SerialUSB and Serial on MKRZERO board](https://forum.arduino.cc/t/difference-between-serialusb-and-serial-on-mkrzero-board/1175679)
**Author:** [@rotermilan-72](https://forum.arduino.cc/u/rotermilan-72)\ **Replies:** 1\ **Last updated:** [October 6, 2023, 1:06pm UTC](https://forum.arduino.cc/t/difference-between-serialusb-and-serial-on-mkrzero-board/1175679 "2023-10-06T13:06:40Z")
What is the difference between SerialUSB and Serial? Best RM --- ## [Arduino MKR ZERO DAC resolution](https://forum.arduino.cc/t/arduino-mkr-zero-dac-resolution/1171105)
**Author:** [@prakash\_design](https://forum.arduino.cc/u/prakash_design)\ **Replies:** 10\ **Last updated:** [September 25, 2023, 6:04pm UTC](https://forum.arduino.cc/t/arduino-mkr-zero-dac-resolution/1171105 "2023-09-25T18:04:30Z")
Hello all, I have created a code for 10 bit DAC using Arduino MKR zero board with SAMD21 controller. Here is the code. it created with default voltage reference 3.3V. i get desired output. Problem statement stated belo… --- ## [Adding a serial uart tx/rx on D4 and D5 of MKRZERO](https://forum.arduino.cc/t/adding-a-serial-uart-tx-rx-on-d4-and-d5-of-mkrzero/1159263)
**Author:** [@marcardui](https://forum.arduino.cc/u/marcardui)\ **Replies:** 21\ **Last updated:** [August 25, 2023, 6:40pm UTC](https://forum.arduino.cc/t/adding-a-serial-uart-tx-rx-on-d4-and-d5-of-mkrzero/1159263 "2023-08-25T18:40:21Z")
Hello, I'm currently attempting to add an additional serial port to my MKRZERO using pins D4 and D5. These are the only available pins left in my project for this purpose, with D4 serving as TX and D5 as RX. Despite inv… [Next page](https://forum.arduino.cc/c/official-hardware/mkr-boards/mkr-zero/140.md?page=1)